Imaging in Pediatric Brain Tumors

Dr. Suhas BResident (MD Radio-diagnosis)

Introduction 20-30% of cancers in children 2500-3000 new diagnoses/year 2nd most common neoplasm Most occur before age 10 years Tumors in infants - usually congenital. Male/Female = 1.3/1.0 60-70% 5 year survival

Analysis of a Potential Brain Tumor Age of the patient Localization - Intra-axial or extra-axial - Compartment - Crossing of the midline CT and MR characteristics - Calcification, fat and cystic - T1, T2, DWI - Contrast enhancement Effect on surrounding structures - Mass effect, edema Solitary or multiple Psuedotumor

Differentiating with Extra-axial lesions

CSF cleft sign Displaced subarachnoid vessels Cortical gray matter between mass and white matter Displace and expand subarachnoid space Broad dural space Bony reaction

Location Supratentorial 25-40% Astrocytoma, low grade 8-20% Astrocytoma, high grade 6-12% Ependymoma 2-5% Mixed glioma 1-5% Ganglioglioma 1-5% Oligodendroglioma 1-2% PNET 1-2% Choroid plexus tumor 1-2% Meningioma 1-2% Germ Cell Tumors 1-2% Other 1-3%

Location (contd.) Infratentorial 45-60% Medulloblastoma (PNET) 20-25% Astrocytoma, low grade 12-18% Ependymoma 4-8% Brain stem glioma, high grade 3-9% Brain stem glioma, low grade 3-6% Other 2-5%

Brain Tumors – signs and symptoms Increased intracranial pressure - symptoms Headache Nausea/vomiting Double vision Head tilt Decreased alertness Lethargy/irritability Poor feeding Endocrine dysfunction Unexplained behavior changes - affect, motivation, energy level

Brain Tumors – Signs/Symptoms

Increased ICP – Signs Papilledema, optic atrophy Loss of vision OFC (head circumference) increased Bulging fontanelles, spreading sutures “Setting sun” sign (Parinaud syndrome) Increased blood pressure, low pulse - herniation?

Posterior Fossa & Brainstem Tumors - Clinical Features

Posterior Fossa primary Ataxia Tremors Dysarthria Stiff neck Papilledema

Brainstem primary Extremity weakness Cranial nerve signs double vision facial weakness swallowing dysfunction

Hemispheric Tumors – Clinical Features

Hemiparesis Hemianopia Aphasia Seizures

Astrocytoma Most common pediatric brain tumor is astrocytoma. – With half being found in the posterior fossa Cerebellar astrocytoma make up 40% of pilocytic astrocytoma Usually occur in the latter half of the first decade – Mean age of 7 years old – Rarely found in children less than 1 year of age M:F = 2:1 Association with NF-1 - more indolent course Symptoms: – Increased ICP (headache, N/V, head size) – Cerebellar deficits Signs: – Papilladema (84%) – Ataxia – Hydrocephalus (85%)

Astrocytoma (contd.) Most commonly involve white matter, may involve cortex CT: - Hypodense or isodense - mass lesion - Calcification (10‐20%) - Hemorrhage, cysts, calvarial erosion are very rare. - No or very minimal enhancement MRI: - Hypointense on T1 - Hyperintense on T2 with - discrete margins - Minimal enhancement

12 year old male child with headache and signs of ICT

Differential diagnosis for astrocytoma: Brain abscess Encephalitis Brain Metastasis Toxoplasmosis Ependymoma

Subependymal Giant cell Astrocytoma

benign tumours (WHO grade I) seen almost exclusively in young patients with tuberous sclerosis (TS) principally diagnosed in patients under 20 years of age They can be either asymptomatic or symptomatic due obstructive hydrocephalus

Subependymal Giant cell Astrocytoma (contd.)

CT: typically appears as an intraventricular mass near the foramen of Monro they are usually larger than 1 cm lesions are iso- or slightly hypoattenuating to grey matter calcification is common and haemorrhage is possible accompanying hydrocephalus may be present often shows marked contrast enhancement (subependymal nodules also enhance) MRI: T1: heterogenous and hypo- to isointense to grey matter T2: heterogenous and hyperintense to grey matter; calcified components can be

hypointense T1 C+ (Gd): can show marked enhancement

NCCT

Post-contrast

T2WIDifferential diagnosis: Central neurocytoma Choroid plexus papilloma Choroid plexus carcinoma

Pleomorphic xanthoastrocytoma type of rare, low-grade astrocytoma (WHO Grade II) found in young patients who typically present with temporal lobe epilepsy. They are rare tumours accounting for only ~ 1% of primary brain tumours almost invariably (98%) located supratentorially, typically located superficially

(peripherally) involve the cortex and overlying leptomeninges. Approximately half are located in the temporal lobe

Pleomorphic xanthoastrocytoma (contd.)

CT:usually present as cortical tumours with a cystic component vivid contrast enhancement no surrounding oedema; scalloping of the overlying bone. A reactive dural involvement expressed by a dural tail sign can be found; Calcifications are rare. MRI:T1 - solid component iso to hypointense c.f. grey matter; cystic component low signal; leptomeningeal involvement seen in over 70% of cases 2T1 C+ (Gd) - solid component usually enhances vividlyT2 - solid component iso to hyperintense c.f. grey matter; cystic component high signal; little surrounding vasogenic oedemaDSA - avascular on angiography

CECT T1WI

FLAIR T2WI

T1 + C

Differential diagnosis:GangliogliomaDNETOligodendrogliomaDesmoplastic infantile ganglioglioma

Oligodendroglioma intracranial tumours that account for 5-25% of all gliomas and 5-10% of all primary

intracranial neoplasms rare tumors in pediatric age group accounting for 0.5 to 1% presentation is most frequently as a result of seizures tumours are typically located supratentorially (85%), involving the white matter most commonly found in the frontal lobes

Oligodendroglioma (contd.) CT: Tumours are of mixed density (hypodense to isodense). High-attenuation areas within the tumour are likely from calcification (70-90% of ODs are

calcified) Calcification can be located centrally, peripherally or they can be ribbon-like The overlying skull may show pressure erosion Only 50% of oligodendrogliomas show enhancement MRI: T1: typically hypointense T2: typically hyperintense (except calcified areas); calcium seen as areas of "blooming" T1 C+ (Gd): contrast enhancement is common but it is not a reliable indicator of tumour

grade, with only 50% of ODs enhancing to a variable degree, and usually heterogeneously DWI – no diffusion restriction

Differential diagnosis: Astrocytoma Ganglioglioma DNET Pleomorphic

xanthoastrocytoma HSV encephalitis

NCCT

CECT

T1WI

T1 + C

T2WI

Ganglioglioma C/F - chronic temporal lobe epilepsy Age- 10-20 years ( < 30 years) Site- superficial hemisphere, temporal lobe Three patterns: - Circumscribed cyst + mural nodule- MC - Solid tumor, expands gyri - Infiltrating, poorly defined mass

Ganglioglioma (contd.)CT - Findings are of a mass which is often non specific. General features include: Iso or hypodense frequently calcified ~35% bony remodeling or thinning can indicate the slow growing nature of the tumour enhancement is seen in approximately 50% of cases (involving the solid non-calcified

component)MRI:T1 - solid component iso to hypointenseT1 C+ (Gd) - solid component variable contrast enhancementT2 – a) hyperintense solid component b)variable signal in the cystic component depending on amount of proteinaceous material or presence of blood products c) peritumoral FLAIR/T2 edema is distinctly uncommonT2* (GE/SWI) - calcified areas (common) will show blooming signal loss

T1WI

DWI T2WI

T1 + C

Differential diagnosis: DNET Pleomorphic

xanthoastrocytoma Desmoplastic infantile

ganglioglioma

Desmoplastic Infantile Ganglioglioma

form of desmoplastic infantile tumours tend to have good prognosis vast majority occur in children less than 1 year of age M:F ratio of approximately 2:1 rapidly increasing head circumference is the most common presentation Seizure activity is uncommon The frontal and parietal lobes are the most common sites.

Desmoplastic Infantile Ganglioglioma (contd.)

CT: manifests as an exceptionally large cerebral hemispheric mass composed of both

cystic and solid portions. solid portion of these large masses is typically slightly hyperattenuating and typically

located along the cortical margin of the mass these masses usually enhance intensely, and may demonstrate a dural tail No calcification MRI: The solid portions typically have the following signal intensity: T1 - isointense to brain parenchyma T2 - isointense to brain parenchyma T1 C+ (Gd) - intense enhancement; dural tail may be seen

T2WI FLAIR

T1WI

T1 + C

Choroid Plexus Papilloma uncommon, benign neuroepithelial intraventricular tumour (WHO grade 1) account for approximately 1% of all brain tumours, 2-6% of all paediatric brain

tumours Approximately 85% of all choroid plexus papillomas occur in children under the age

of 5 years. Most common brain tumors in children under 2 years Fourth ventricular tumors cause obstructive hydrocephalus with headache & ataxia CPPs that arise in the foramen of Luschka or CP angle may cause cranial nerve

palsies The most common location is the lateral ventricle trigone ( atrium ) – 50 % - fourth ventricle – 40 % - third ventricle & cerebellopontine cistern – 10 % The primary neoplasm sheds tumor & seeds the CSF pathways ( drop metastases )

Choroid Plexus Papilloma (contd.)CT:The tumours are usually well-defined lobulated massesiso- or somewhat hyperdense compared to the adjacent brain. There is associated hydrocephalus. They usually homogeneously enhance, demonstrating with an irregular frond-like pattern, resulting in a cauliflower-like appearance. Fine, speckled calcification is seen within the tumour in approximately 25% of casesMRI:T1 - typically isointense c.f. to adjacent brain. May be somewhat hypointenseT2 - iso to hyperintense, small flow-voids may be seen within the tumourT1 C+ (Gd) - marked enhancement, tends to be homogenousMRS - decreased NAA, increased ChoAngiography: demonstrate intense vascular blush on angiography. Enlarged choroidal arteries may be seen feeding the tumour, with shunting

T1WI T2WI T1 + C

Differential diagnosis: Choroid plexus carcinoma Choroid plexus metastases Medulloblastoma ATRT Papillary anaplastic

ependymoma Central neurocytoma

Choroid Plexus Carcinoma malignant neoplasm arising from the choroid plexus (WHO grade III) significantly poorer prognosis than choroid plexus papilloma (CPP) 10 – 20 % of all choroid plexus neoplasms Almost all occur in infants & children 2 – 4 years of age Symptoms are due to hydrocephalus & less commonly due to parenchymal invasion There is an association with Li-Fraumeni syndrome They almost always arise in the lateral ventricles & infiltrate the adjacent brain

parenchyma

Choroid Plexus Carcinoma (contd.)

CT:choroid plexus carcinomas are heterogeneous and typically iso to hyperdense to grey matterCalcification may be seen in 20-25% of cases.Contrast enhanced is usually prominent but heterogeneous with areas of necrosis and cyst formation evident. MRI:T1: iso- to hypointenseT2: iso- to hypointense with hyperintense necrotic areasT2* GRE: blooming from calcifications/haemorrhageT1 C+ (Gd): can show marked, heterogeneous enhancement. The tumours may have CSF seeding

Differential diagnosis:Choroid Plexus papillomaCentral neurocytomaChoroid plexus meningiomaPNET GBM

NCCT

T1WI

T1 + C T2WI

Central Neurocytoma WHO Grade II neuroepithelial intraventricular tumour typically seen in young patients (16-40 years of age), and generally have a good

prognosis accounts for less than 1% (0.25-0.5%) of intracranial tumours symptoms of increased intracranial pressure, headaches being most frequent, or seizures associated with sudden death secondary to acute ventricular obstruction sudden presentation due to intraventricular haemorrhage Variant – ganglioneurocytoma Typical locations include: - lateral ventricles around foramen of Monro (most common): 50% - both lateral and 3rd ventricles: 15% - bilateral: 15% - 3rd ventricle in isolation: 5%

Central Neurocytoma (contd.) CT:Central neurocytomas are usually hyperattenuating compared to white matterCalcification seen in over half of cases, usually punctate in nature Cystic regions are frequently present, especially in larger tumours. Contrast enhancement is usually mild to moderate. Accompanying ventricular dilatation often present. MRI:T1 - isointense to grey matter, heterogenousT1 + C - mild-moderate heterogeneous enhancementT2/FLAIR - typically iso to somewhat hyperintense compared to brain numerous cystic areas (bubbly appearance), many of which completely attenuate on FLAIRProminent flow voids may be seen SWI – bloomingMRS – strong choline peak

T1WI T1 + CT2WI

DWI FLAIR

Differential diagnosis: Ependymoma Intraventricular meningioma Subependymal giant cell

astrocytoma Choroid plexus papilloma Choroid plexus carcinoma Oligodendroglioma

Pineocytoma

relatively benign pineal parenchymal tumour (WHO grade I tumor) relatively good prognosis encountered at any age but mostly occur in young adults in the second decade of

life clinical presentation is mainly from obstructive hydrocephalus secondary to

compression of the tectum of the midbrain compression of the superior colliculi can also lead to a characteristic gaze palsy,

known as Parinaud syndrome

Pineocytoma (contd.)CT:intermediate density, similar to adjacent brainPineal calcifications tend to be dispersed peripherallyMRI:T1: isointense to brain parenchymaT2:solid components are isointense to brain parenchymaareas of cystic change are commonsometimes the majority of the tumour is cysticT1 C+ (Gd): solid components vividly enhance

FLAIR

T1 + C

T1WI

T2WI

Differential diagnosis: Pineal cyst Pineoblastoma Pineal papillary tumor Germinoma Teratoma Astrocytoma of pineal gland

Pineoblastoma primitive neuroectodermal tumours (PNET) located in the pineal region most agressive and highest grade tumour among pineal parenchymal tumours typically found in young children, with both sexes being equally affected well established association with hereditary retinoblastomas Patients with bilateral retinoblastoma 5-15% develop midline (suprasellar or

pineal) neuroblastic tumours, referred to as trilateral retinoblastoma. always associated with obstructive hydrocephalus highly malignant tumours prone to CSF seeding

Pineoblastoma (contd.) CT: Large poorly defined masses (>4 cm) Tendency to directly involve adjacent brain structures The solid component tends to be slightly hyperdense compared to adjacent brain. Classically, they are described as having peripherally disperse or "exploded"

calcification MRI: T1- isointense to hypointense to adjacent brain T2 - isointense to adjacent brain; areas of cyst formation or necrosis may be present T1 C+ (Gd) - vivid heterogenous enhancement DWI - restricted diffusion due to dense cellular packing

T1WI

T2WI

T1 + C

Differential diagnosis: Pineocytoma Pineal papillary tumor Germinoma Astrocytoma of pineal

gland Pineal cyst

DNET Dysembryoplastic neuroepithelial tumor- benign, focal, intracortical mass

superimposed on background of cortical dysplasia vast majority are centered in cortical grey matter, arise from secondary germinal

layers C/F- longstanding partial complex seizures Age- < 20 years Site - temporal lobe ( amygdala/ hippocampus) 60%, frontal lobe 30%, caudate

nucleus, cerebellum and pons

DNET (contd.)DNETs are typically predominantly cortical and well circumscribed tumours. CT: if cortical may scallop the inner table of the skull vault (44-60%), but no erosion the cranial fossa can be minimally enlarged at times calcification in ~30% (more common histologically) low density; no enhancement MRI: T1 - generally hypointense c.f adjacent brain T1 C+ (Gd) - may show enhancement in ~20-30% of cases; enhancement may be

heterogeneous or a mural nodule; focal punctate or ring enhancement- 20% T2 - generally high signal; high signal 'bubbly appearance‘ FLAIR- hypo/ isointense with bright rim; no peritumoral edema DWI- lacks restricted diffusion

T2WI

T1WI

T1 + C

DWI

FLAIR

Differential diagnosis: Ganglioglioma Pleomorphic xanthoastrocytoma Pilocytic astrocytoma Desmoplastic infantile

ganglioglioma Oligodendroglioma Choroid fissural cyst HSE and limbic encephalitis Mesial temporal sclerosis

Intracranial Germinoma also known as dysgerminomas or extra-gonadal seminomas tumours of young patients with a peak incidence of 10-12 years of age account for 3-5% of paediatric intracranial tumours most common tumour of the pineal region accounting for approximately 50% of all

tumours male to female ratio of 5-22:1 tend to occur in the midline, either at the pineal region (majority) or along the floor

of the third ventricle/suprasellar region obstructive hydrocephalus and Parinaud syndrome involvement on the pituitary infundibulum leads to diabetes insipidus (most

common), hypopituitarism (common) or optic chiasm compression or signs of intracranial hypertension.

Intracranial Germinoma (contd.)

CT: Germinomas are soft tissue density masses high cellularity results in a degree to hyperdensity compared to adjacent brain typically seen filling and expanding the infundibular recess and supraoptic recess subtle abnormal pituitary stalk enhancement and thickening presence of calcification in the pineal region is a useful marker of an underlying tumour MRI: MRI demonstrates a soft tissue mass, typically ovoid or lobulated in contour, engulfing the calcified

pineal gland with the following signal characteristics T1 - isointense or slightly hyperintense to adjacent brain T2 - isointense or slightly hyperintense to adjacent brain; may have areas of cyst formation; may

have areas of haemorrhage (low signal); have a predilection to invade adjacent brain (oedema); central calcification appears low signal (engulfed pineal gland)

T1 C+ (Gd): vivid and homogeneous

T1WI

T1 + C

T2WI FLAIR

Differential diagnosis:• Pineocytoma• Pineoblastoma• Papillary tumor of pineal gland• Astrocytoma of pineal gland• Meningioma near pineal gland

Intracranial Teratoma account for the largest proportion of fetal intracranial neoplasms divided into two broad categories: - intra- and extra-axial Intra-axial teratomas present antenatally due to increasing head circumference;

tend to occur supratentorially Extra axial teratomas usually present in childhood or early adulthood; commonly

arise in the pineal or suprasellar regions; obstructive hydrocephalus, Parinaud syndrome

Intracranial Teratoma (contd.) CT: Intracranial teratomas are often seen as large lesions at presentation tumours typically demonstrating a mixture of tissue densities and signal intensity demonstrate at least some fat and some calcification, which is usually solid / "clump-

like" They usually have cystic and solid components, contributing to an irregular outline. Solid components demonstrate variable enhancement MRI: T1 - hyperintense components due to fat and proteinaceous/lipid rich fluid;

intermediate components of soft tissue; hypointense components due to calcification and blood products

T1 C+ (Gd) - solid soft tissue components show enhancement T2 - again mixed signal from differing components

T1WI

T2WI

FLAIR T1 + C

Differential diagnosis:sPNETATRTChoroid plexus carcinomaIntracranial lipomaIntracranial dermoidCraniopharyngioma

Hypothalamic Hamartoma Rare congenital condition consisting of a mass of disorganized neuronal or glial

tissue on or near the hypothalamus. The size varies from less than 1 cm to more than 3 cm. These lesions can be pedunculated or sessile. Present with precocious puberty, gelastic seizures,visual problems and behavioral

problems associated with Pallister-Hall syndrome which is a syndrome consisting of multiple

malformations, including polydactyly and imperforate anus. Central precocious puberty is also frequently encountered in these children small pedunculated growths contiguous with posterior hypothalamus, between the

tuber cinereum and mamillary bodies. They fill the free space between the optic chiasm and pons and usually do not distort

the hypothalamus or other parts of the base of the brain unless they are very large.

Hypothalamic Hamartoma (contd.)

CT:nodule of soft tissue iso-attenuating to grey matterwithout calcification or contrast enhancementMRI:T1 - isointense to cerebral cortex T1 C+ (Gd) - no contrast enhancement T2 - iso- to hyperintense to cerebral cortex; the higher the proportion of glial cells, the higher the T2 signal MRS - reduced NAA/Cr, increased myoinositol, increased Cho/Cr compared to the amygdala has also been reported

Differential diagnosis: Hypothalamic-chiasmatic

glioma

T1WI T2WI T1 + C

Craniopharyngioma Arise from squamous epithelial rests along the involuted hypophyseal- Rathke’s duct 3% of intracranial neoplasms. 15% of supratentorial and 50% suprasellar tumors in children M>F Bimodal age distribution- 1st- 5-15 yrs and 2nd peak- 4th-6th decade Types- Adamantinomatous and papillary

Craniopharyngioma (contd.) Radiography: Lateral skull- Amorphous sellar & suprasellar Ca++, sellar

enlargement, dorsum sellae & clinoid erosion NECT:

- Admantinomatous : 90% mixed (solid & cystic) 90% calcify

- Papillary : Often solid , isodense, rarely calcifies CECT: 90% enhance (solid + capsule) CTA: Displacement & encasement of circle of Willis

Craniopharyngioma (contd.) MRI: Multilobulated, multicystic suprasellar masses. T1WI - cystics areas may be isointense or have high or low SI as compared to

brain T2WI - both solid and cystic components tend to be hyperintense but cystic

component tend to have higher SI. Solid part has granular appearance on pre-contrast T1WI and may show heterogenecity as a result of small cysts and calcification.

Post-contrast- solid part enhance heterogenously. Thin walls of cysts nearly always enhance

Papillary type - entirely solid. Heterogenous appearance and enhancement. MRS - to differentiate from suprasellar astrocytoma which shows large Choline

peak and reduced but present NAA peak

17 year old male with headache and impaired vision

Intracranial Lipoma Lipoma are not true neoplasm, classified as choristomas ( mass of tissue that would

be histologically normal for an organ or body other than the site at which it is located)

ETIOLOGY- results from abnormal persistense/ maldifferentiation of meninx primitiva

GROSSLY- 2 Types - Tubulonodular lipomas- are large bulky round/cylindrical masses. Commonly ass.with corpus callosum dysgenesis, frontal lobe anomalies & cephaloceles - Curvilinear lipomas- are thin posteriorly situated, curve around the splenium. Corpus callosum is usually normal.

Intracranial Lipoma (contd.) Incidence- 0.1-0.5% of primary brain tumours. 5% of corpus callosum tumors Neither age nor gender related Location- at or near midline- 80-95%. Common sites are pericallosal area,

quadrigeminal, interpeduncular, chiasmatic, sylvian cisterns, cerebellopontine angle.

CT- very low density mass(-50 to-100 HU), curvilinear or nodular calcification. With ass.congenital malformations.

Show no enhancement MRI- Hyperintense on both T1W & fast spin-echo T2WI. Low signal foci represent

calcification, traversing arteries or nerves. Fat- suppression technique used to confirm diagnosis.

18 year old male with head injury

Rathke Cleft cyst Etiology - Primitive stomodeal (Rathke’s pouch) remnant Pathology Gross: - Cyst with variable contents (serous, mucoid) Microscopic: - Columnar/cuboidal epithelium; goblet cells often present, squamous cells sometimes seen Incidence - <1% of nontraumatic intracranial masses; small cysts common at autopsy

Rathke Clef cyst (contd.)Age and gender- Any age but mostly adults 40 – 70 years; F:M = 2-3:1Location- 70% both infra/suprasellar; 25% to 25% intrasellar; <5% completely suprasellar

CT: 75% hypodense to brain; noncalcified; 50% rim (capsular)enhancement

MR: Most common = hyperintense to brain on T1WI, with variable signal on T2WI

Differential diagnosis:Arachnoid cyst, noncalcified craniopharyngioma, cystic pituitary adenoma, inflamatory cyst

14 year old female with Diabetes Insipidus

Epidermoid

Irregularly lobulated Insinuating Common in CP angle, 4th ventricle, supra & parasellar regions. Intra cerebral < 10% Incorporation during 4-5th week of development. No dermal appendages & hair follicles. Dermoids contain dermal appendages.

Epidermoid (contd.) Similar to CSF on T1 & T2 High signal in case of white epidermoids Incomplete nulling on FLAIR DWI – Restriction No enhancement, Thin enhancement at the periphery 25% may show rim enhancement White epidermoid – More protein and debris ---- high signal on T1

& CT.

T1 + C

T1WI DWI T2WI FLAIR

Differential diagnosis: Dermoid Acoustic neuroma Craniopharyngioma Arachnoid cyst

Dermoid Incidence - Uncommon (0.04% to 0.6% of primary brain tumors) Age - 30 to 50 years; slight male predominance Location - Midline - Parasellar, frontobasal most common intra-cranial sites - Vermis, 4th ventricle most common infra- tentorial sites - Subarachnoid spread from ruptured cyst

Dermoid (contd.) CT: appear as well defined low attenuating (fat density) lobulated masses. Calcifications may be present in the wall. Enhancement is uncommon, and if present should at most be a thin peripheral rim. Very rarely they demonstrate hyperdensity thought to be due to a combination of

saponification, microcalcification and blood products.

MRI: Typically follow fat density on all sequences No enhancement; extensive pial enhancement may be present in chemical

meningitis due to ruptured cyst

TT1WI FLAIR T2WI

DWI

Differential diagnosis: Intracranial lipoma Intracranial teratoma Craniopharyngioma

Pilocytic Astrocytoma 5-10% of all glioma 75% of cerebellar Astrocytomas are of the Pilocytic type MC primary brain tumour in children Slowly growing tumour WHO Grade 1 Clinically aggressive but malignant transformation is uncommon 5 yr survival rate is 86-100% Associated with NF-1 (Optic pathway, 15-21%) Frequently causes obstructive hydrocephalus Pilomyxoid astrocytoma is a variant (WHO grade 2 tumor), most commonly involves

hypothalamus and optic chiasm

Pilocytic Astrocytoma (contd.) Cystic cerebellar mass with enhancing mural nodule Enlarged optic nerve/chiasma/adjacent to 3rd ventricle/brainstem (dotted I sign) Less than 10% - solid. May enhance in a homogeneous or a heterogeneous fashion Approximately 50% are simple cysts with a single mural nodule No histological evidence of tumor is present in the cyst wall. Removal of the mural

nodule in this tumor variety may be sufficient for treatment. About 40-45% consist of multilocular cysts In these cases, histologic evidence of

tumor is present in the cyst wall. Contrast enhancement is strong Calcification (10%)& Hemorrhage are rare T1: iso to hypointense solid component compared to adjacent brain T2: hyperintense solid component compared to adjacent brain

7 year old male with c/o nystagmus and gait abnormality

16 year old male with headache and raised ICT

Differential diagnosis for Pilocytic Astrocytoma: Medulloblastoma ATRT Ependymoma Hemangioblastoma Ganglioglioma Pleomorphic xanthoastrocytoma Cerebellar abscess

Medulloblastoma Medulloblastoma - posterior fossa PNET - supratentorial Pineoblastoma - pineal region 3% of brain tumors 15 – 20% of childhood malignant brain tumors 30 – 40% of childhood posterior fossa tumors Typically occur in the posterior fossa (75%) 25% in lateral cerebellum Age: 5-15y M:F = 2:1 propensity to disseminate through CSF - 1/3 with metastatic disease at diagnosis - Can spread to lung, liver, BM, bone, LN’s – rare

Medulloblastoma (contd.) CT - a heart or pear shaped hyperdense midline vermian mass abutting the roof of

the fourth ventricle, with perilesional oedema, variable patchy enhancement and hydrocephalus.

Brainstem -displaced anteriorly. Cystic change, haemorrhage and calcification may be seen. Typical features - seen in only 30 % of cases Atypical features are common - Cystic changes (65%) - Isodense attenuation on NECT (3%) and abnormal contrast enhancement

Non Contrast Post contrast

Medulloblastoma (contd.)

MRI: Hypointense on T1 Variable hypo‐ to hyperintense on T2 Variable enhancement restricted diffusion on diffusion-weighted imaging

T1

T1 + C

FLAIR

Gradient Echo DWI

Differential diagnosis of posterior fossa tumour with ct hyperdensity and t2 hypointensity

Medulloblastoma/primitive neuro ectodermal tumour/atypical teratoid- rhabdoid tumour /Choroid plexus carcinoma

Ewing's sarcoma Chondrosarcoma Chordoma Lymphoma Langerhans' cell histiocytosis

Metastatic Medulloblastoma Disseminated Medulloblastoma - 20- 50% 2/3rd to other CNS locations 1/3rd extra cranial primarily to bone(typically lytic) Disseminated CSF metastasis coats the brain like frosting on cake ,giving

rise to ZUCKERGUSS ( sugar icing) – Entire neuraxis should be scanned. Metastasis along Virchow Robin spaces

Sugar coating or Zuckerguss

Ependymoma Third most common pediatric brain tumor Mean age at diagnosis is 4‐6 years – 1/3 of which are diagnosed before age 3. Arise from the ependymal cells that line the ventricle of the brain and spinal cord May have leptomeningeal spread of brain/spine, CSF at the time of diagnosis NF2 patients commonly have spinal ependymomas not intracranial. Can be seen with Li‐Fraumeni syndrome (p53) and Turcot syndrome (APC gene) Presenting symptoms are – disequilibrium , nausea , vomiting & headache &

signs are ataxia & nystagmus Location - 60 % are infratentorial - > 90 % are in fourth ventricle , medulla &

cerebellopontine angle cisterns make the remaining; 40 % are supratentorial – extraventricular loction more common ( 2/3rd to 3/4th ) than intraventricular sites

Ependymoma (contd.) Types: Classic Papillary Myxopapillary - Conus medullaris or filum terminale of the spinal cord Subependymoma – represent a transitional form between ependymoma &

astrocytoma. Ependymoblastoma- from primitive neuroepithelial precursor cell & shows

ependymal differentiation. Clear Cell Tanycytic Giant Cell Anaplastic

Ependymoma (contd.)

CT: Most are isodense 50 % cases show calcification Overt hemorrhage is uncommon Mild to moderate inhomogenous

enhancement is seen in 70 % of cases

Example 1 Example 2

Ependymoma (contd.)

MRI: The MR differentiation of ependymomas from other gliomas is related to their

location & morphology only. The post fossa ependymoma is lobulated soft tissue mass that appears to form a

cast or mold of the fourth ventricle & extrudes through its outlet foramina into the adjacent subarachnoid cisterns

The solid components are hypo – to isointense compared to brain on T1WI & hyperintense on proton density & T2WI

The cystic portions are slightly hyperintense to CSF on T1WI & hyperintense to brain on T2WI

Intratumoral heterogeneity may represent necrosis , calcification , tumor vascularity or blood degradation products

T2WI T1WI

T1 + C

FLAIR

DWI

Differential diagnosis for ependymoma: Medulloblastoma Choroid plexus papilloma Central neurocytoma Pilocytic astrocytoma

Brainstem Glioma Represent 10‐20% of all CNS tumors in children Peak presentation at 7‐9 years Classic triad of physical findings (all three seen in 1/3 of c

ases): – Cranial nerve palsies, ataxia and Long tract signs Types: Diffuse intrinsic brainstem glioma - Most commonly located in the Pons - Account for 80% of brainstem tumors Focal Occupy less than 50% of brainstem subregion. Often clearly distinguishable from surrounding brainstem. Subtypes include dorsal exophytic, cervicomedullary and

midbrain

Brainstem Glioma (contd.)

CT: Typically hypodense with little, if any, enhancement.

MRI: Modality of choice Hypointense on T1 Hyperintense on T2 Enhancement is variable and depends on the type an

d grade of the tumor – Diffuse intrinsic tumors rarely enhance.

Differential diagnosis: Rhombencephalitis ADEM LCH Tuberous sclerosis NF 1 PNET Ependymoma

T1WI

T2WI

FLAIR T1 + C

Atypical Teratoid Rhabdoid Tumor uncommon malignant intracranial tumors, representing only 1.3% of primary CNS

tumors in the pediatric population (WHO Grade IV tumour) vast majority of cases occurs in young children less than two years of age can occur anywhere in the central nervous system (CNS) including the spinal cord. infratentorial: ~50% - cerebellum (most common), brainstem supratentorial - cerebral hemispheres, pineal gland region, septum pellucidum and hypothalamus

ATRT (contd.) CT : often isodense to gray matter may demonstrate heterogeneous enhancement calcification is common may show associated obstructive hydrocephalus

MRI: Can show necrosis, multiple foci of cyst formation and sometimes haemorrhage: T1: iso- to slightly hyperintense to grey matter (haemorrhagic areas can be more hyperintense) T2: generally hyperintense (haemorrhagic areas can be hypointense) T1 C+ (Gd): heterogeneous enhancement MRS - Cho: elevated - NAA: decreased

Differential diagnosis for ATRT: Supratentorial PNET Intracranial teratoma Medulloblastoma Choroid plexus carcinoma Malignant glioma

Pre-contrast Post-contrast

T1WI

T1 + CT2WI

DWI

Hemangioblastoma Presentation- headache, disequilibrium, dizziness Age- 40-60 years VHL associated occur in younger age group

IMAGING FINDINGS: Best diagnostic clue - intraaxial posterior fossa mass with cyst, enhancing mural

nodule abutting pia Location - cerebellar hemisphere- 80% - vermis-15%, medulla & 4th ventricle- 5%

Hemangioblastoma (contd.) CT: low density cyst + isodense nodule intensely enhancing nodule Cyst wall doesn’t enhance MRI:T1WI- nodule isointense to brain, cyst slightly hyperintense compared to CSFT2WI- both nodule & cyst are hyperintensePost contrast- intensely enhancing noduleMRS- Raised lipid and choline- Absent NAA and lactate

Differential Diagnosis: Pilocytic astrocytoma AVM Ependymoma Medulloblastoma

16 year old male with symptoms and signs of raised ICT

Acoustic Schwannoma Can be unilateral or bilateral. - If there are bilateral acoustic schwannomas this is diagnostic for NF2 -Unilateral Acoustic schwannoma and a first degree relative with NF2 is diagnostic of NF2 Can be sporadic or associated with NF2. – Sporadic variety is very rare in pediatric population Account for 0.8% of pediatric brain tumors NF2 associated schwannomas present with auditory complaints only 30% of the time. As opposed to the sporadic variant, NF2 associated schwannomas grow faster and hav

e  increased invasion of the nerve

Acoustic Schwannoma (contd.) CT: show erosion and widening of the internal acoustic canal density of these tumours on non-contrast imaging is variable Contrast enhancement is present, but can be underwhelming, especially in larger

lesions with cystic components MRI: T1 - slightly hypointense cf. adjacent brain (63%); isointense cf. adjacent brain (37%);

may contain hypointense cystic areas T2 - heterogeneously hyperintense cf. to adjacent brain; cystic areas fluid intensity

and may have associated peritumoural arachnoid cysts 3 T1 C+ (Gd) - contrast enhancement is vivid but heterogeneous in larger tumors

T1WI

T1 + C

FLAIR

T2WI

Differential diagnosis: Epidermoid Ependymoma Meningioma

Intracranial Teratoma account for the largest proportion of fetal intracranial neoplasms divided into two broad categories: - intra- and extra-axial Intra-axial teratomas present antenatally due to increasing head circumference;

tend to occur supratentorially Extra axial teratomas usually present in childhood or early adulthood; commonly

arise in the pineal or suprasellar regions; obstructive hydrocephalus, Parinaud syndrome

Intracranial Teratoma (contd.) CT: Intracranial teratomas are often seen as large lesions at presentation tumours typically demonstrating a mixture of tissue densities and signal intensity demonstrate at least some fat and some calcification, which is usually solid / "clump-

like" They usually have cystic and solid components, contributing to an irregular outline. Solid components demonstrate variable enhancement MRI: T1 - hyperintense components due to fat and proteinaceous/lipid rich fluid;

intermediate components of soft tissue; hypointense components due to calcification and blood products

T1 C+ (Gd) - solid soft tissue components show enhancement T2 - again mixed signal from differing components